This is the town that ceased to exist. Where Balakot once stood, today there is a pile of rubble. Everything is gone: houses, shops, businesses and all the schools.

To get through the ruins you have to scramble over the great mounds of concrete and past the blue tiles someone once chose for their kitchen. One man found a child's exercise book in the rubble and sat silently leafing through the pages. Under every mound lie the bodies.

The Pakistani government said yesterday that Saturday's deadly earthquake had wiped out a generation.

"They say that the earthquake killed 19,000 people across Pakistan. I think it may have killed 20,000 in Balakot alone," said Sohrab Khan, a volunteer who had come to help with the relief effort.

As the world rushed doctors, helicopters, food, tents and sniffer dogs to Pakistan last night and survivors were hauled from the wreckage in Islamabad, the death toll across three countries topped 22,000. And tens of thousands more have been injured. Aid agencies said more than 120,000 people, many of them children, were in urgent need of shelter and up to four million could be homeless.

In northern Pakistan, entire communities are gone. When they clear the landslides that block the roads, they find they lead nowhere, to graveyards of rubble. And it is the children who have borne the brunt of it. Even the few who have not been crushed to death in their classrooms face an uncertain future. Many will have been orphaned, most have lost the adults that fed, clothed and sheltered them.

Over at the great mountain of shattered concrete that was once Balakot school, they were still digging yesterday. There were 317 children inside when the earthquake struck. Only two have come out alive. There were no rescue teams at the school, just the local people scrabbling with their bare hands, trying to cut away the iron reinforcement rods with a simple hacksaw.

"Quiet! Quiet!" someone shouted. "We can hear one of them." And the great crowd that had gathered on top of the building's remains, many of them parents of the children inside, fell silent. Then, as one, they began to pray for the children still trapped inside, a soft murmur going up as the layers of concrete trembled perilously under their feet. But few of those children can survive much longer. Most are probably dead, and Balakot is consumed with anger that still no help has arrived from the government.

Mohammed Azrael sat on the edge of the ruins of the school. He was walking along the road in front of the school with his wife, Khatoom, and daughter, Shamim, when the earthquake came. "I started running but when I looked back they were gone," he says. "The schools collapsed on top of them." He has no other children and his house is destroyed. He is sitting and waiting.

All day long you see the bodies in Balakot. People digging for survivors keep finding only the dead. They carry them out for burial on stretchers. One man carried his dead daughter in his bare arms, the tiny girl was not heavy enough to need a stretcher. Her head lolled lifelessly. He wept as he carried her.

You could see the great columns of people moving towards Balakot long before you reached the ruined town. They snaked around the hillsides and down into the river valley, thousands of people marching with pick axes and shovels over their shoulders, bundles of food and warm blankets for survivors under their arms. It was a vast column of volunteers, a people's army coming to do what the people say the government and military have failed to do: to help.

The contrast with New Orleans after Hurricane Katrina could not be more marked. In the US, when government help did not arrive, armed looters roamed the streets and survivors had to huddle together for safety. In Pakistan, people have arrived from all over the country to help in the relief effort. They have simply abandoned their jobs. Some hitched lifts, clinging dangerously on to the sides of trucks and mini buses as they wound around the hairpin curves over a sickening drop to the valley below. Others simply walked for hours across the hills in the blistering sun, denying themselves even water because it is the Muslim fasting month of Ramadan.

Ibrahim Habib had come from Peshawar, close to the Afghan border, four hours' drive away. He has no friends or relatives in the town. "I came because they are Muslims in need. I came because of Islam. I came all the way from Peshawar," he said. But he was angry. "Where is the army?"

There are few police on the streets: there don't need to be. In this corner of Pakistan, no house is without a Kalashnikov, it is usually unsafe for Westerners even to venture here. But yesterday an air of solidarity prevailed on the streets. Everyone was here for one reason.

Even the Islamic militants were arriving to help. At least three people were trapped alive in the ruins of a hotel building in the centre of town.

Wedged in a narrow space under the ruins, which could have collapsed on him at any time, was a young man in combat trousers. He was a militant from Harkat ul-Mujahideen, (the Movement for Holy Warriors) a faction backed by the government that smuggles militants into Indian-administered Kashmir and is listed as a "terrorist" group in the West. Such groups maintain training camps in this area.

"We were at the Harkat ul-Mujahideen office when the earthquake hit," said Tabark Hussein, 29, a militant who says he has spent six years fighting "on the border" with India. "Our commanders told us, go to the affected areas and help. We have fanned out across the region, we are in lots of affected towns." One man came up in tears. "I came here to help but what can I do?" he said. "We have no special equipment to dig for people. There are 300 children buried in the school and we can't help them ... what can I say? I don't have the words. There are no government officials here. Just helpless people with their bare hands."

Balakot used to be a tourist town, where Pakistanis came to escape the heat of the plains in summer. The location is hauntingly beautiful, at the end of a long valley carved out between towering mountains, with a torrent of a river hurtling through it. But after the earthquake, the area has turned deadly. The road was cut off by landslides.

Yesterday, the thousands of volunteers who came braved new landslides, small rocks and debris falling down on to them from the precarious hillsides. So many of the affected areas are in remote valleys like this, cut off from the outside world.

The only visible sign of the Pakistani military were helicopters that came in to airlift the seriously injured to hospital. In the afternoon, a French rescue team arrived at the school. But for the other survivors, there was nothing, and at night it is cold.

Mohiuddin Mohammed Ali, who has five children, said: "We need shelter. All the houses are destroyed. We have nowhere to go and we need food." Mr Ali was born here. After serving in the navy, he returned to enjoy early retirement. But now he says he will leave and never return. "No one can rebuild Balakot," he said. "We don't want to be here. Everything we had here is gone."